In D.C., a crowd that appeared to number in the thousands, gathered in front of the White House and held signs that read, "Protect People Not Guns," and "Thoughts and Prayers Don't Save Lives, Gun Reform Will." President Donald Trump was traveling in Los Angeles at the time of the demonstration.

At 10 a.m., those who gathered on Pennsylvania Avenue and those at schools across the country observed 17 minutes of silence -- one minute for each victim in the Florida school shooting. The large group then marched down Pennsylvania Avenue to the U.S. Capitol grounds chanting "Hey, hey, ho, ho. The NRA has got to go" and "What do we want? Gun control! When do we want it? Now!"

Once the group reached the Capitol they were joined by lawmakers outside for a rally.

Students at Marjory Stoneman Douglas High School gathered on the campus football field to protest gun violence amid the nationwide school walkouts. The group shouted "MSD! MSD!" and engaged in a group hug Wednesday morning as they rallied to continue putting pressure on federal lawmakers to enact gun control legislation.

Other protests planned in coming weeks include the March For Our Lives rally for school safety, which organizers say is expected to draw hundreds of thousands to the nation's capital on March 24. Another round of school walkouts is planned for April 20, the 19th anniversary of the Columbine High shooting in Colorado.

Historians said the demonstrations were shaping up to be one of the largest youth protests in decades.

"It seems like it's going to be the biggest youth-oriented and youth-organized protest movements going back decades, to the early '70s at least," said David Farber a history professor at the University of Kansas who has studied social change movements. "Young people are that social media generation, and it's easy to mobilize them in way that it probably hadn't been even 10 years ago."